The present disclosure relates to semiconductor devices and, more particularly, to semiconductor devices including a field effect transistor. A semiconductor device may include an integrated circuit having metal oxide semiconductor field effect transistors (MOSFETs). As the semiconductor device becomes highly integrated, MOSFETs may be scaled-down in size, which may result in deterioration of operating characteristics of the semiconductor device. For example, a process margin (e.g., spacing) of metal lines in the semiconductor device may decrease, which may result in deterioration of operating characteristics. Accordingly, various research has been developed to manufacture semiconductor devices having high performance while overcoming limitations due to the high integration of semiconductor devices.